Analytes Compounds within the scope of EURL POPs

Since its beginnings as Community Reference Laboratory for PCBs and Dioxins in 2006, EURL POPs has steadily widened its scope of analytes: First, with the addition of PBDEs as major brominated contaminant group, then with CPs as long-term research project and finally PFASs and several chlorinated and brominated compound groups as part of the new mandate covering halogenated POPs. Though the emphasis on certain compound groups has shifted over time depending on new risk assessments or regulatory efforts in the European Union, EURL POPs strives to constantly improve all existing analysis methods and train all member states in the relevant techniques, if necessary. A short overview of the current analyte spectrum is given here, including general descriptions, legal requirements and links to related EURL POPs activities and scientific output.

PFASs What are Per- and Polyfluoroalkyl Substances (PFASs)?

Per- and polyfluoroalkyl substances (PFAS) are a group of anthropogenic organic compounds consisting of a hydrophobic fluorinated alkyl chain and a hydrophilic functional group. This class of compounds includes a large number of substances, namely all that contain the perfluoroalkyl moiety (CnF2n+1). In polyfluorinated substances, a CF2 moiety is replaced by a CH2 group.

PFASs have been produced since the 1950s and are widely used as monomeric or polymeric substances in direct or indirect uses and subsequently have been found in the environment but also throughout the food chain and in human tissue. Two of the most frequently used PFASs have been listed in the annexes of the Stockholm Convention - PFOS in 2009 and PFOA in 2019 – with the aim of elimination of production and uses. Perfluorohexane sulfonic acid (PFHxS) is recommended for listing in the Stockholm Convention (probably in 2021).

PFOS structure

Toxicity and exposure

The International Agency for Research on Cancer (IARC) has not evaluated PFOS as to its carcinogenicity to humans yet (status: May 2020), but classified PFOA as possibly carcinogenic to humans (Group 2B) [1]. In the EU, PFOA has a harmonised classification as a suspected carcinogen and presumed human reproductive toxicant [2]. In the most recent EFSA Scientific Opinion in 2020, four PFAS have been assessed: PFOS, PFOA, PFHxS and perfluorononanoic acid (PFNA) [3]. The resulting updated Health Based Guidance Values led to a sum TWI for PFOS, PFOA, PFNA, and PFHxS in food of 4.4 ng/kg bw/week.

Analysis at EURL POPs

EURL POPs is developing and optimizing multi-methods in order to monitor PFAS in feed and food. Analytes of interest were selected based on toxicological significance, occurrence and availability of reference standards. A frequently used extraction method is solid liquid extraction combined with solid phase extraction (SPE) and/or dispersive solid extraction (dSPE). Analytes are measured by LC-MS/MS.

The new sum TWI is much lower than what was concluded in 2008 and 2018 and has consequences for laboratories, as lower limits of quantification (especially for fruits and vegetables) have to be achieved. A number of different analytical approaches exist and will be checked with regard to options for lowering the achievable LOQs and to expand the range of analytes. The development of methods for analysis of the relevant PFAS in feed is currently ongoing. All method development is done in accordance with requirements by ISO 17025 accreditation.

Legal requirements

There are currently no legal requirements for PFASs in food and feed, though maximum levels based on the new sum TWI are being discussed.

References

  • [1] International Agency for Research on Cancer, 2017. IARC Monographs 110: 37 ff.

  • [2] EFSA, 2008. EFSA Journal 6 (7):653.

  • [3] EFSA CONTAM Panel et al., 2020. EFSA Journal 18(9):6223.

Toxicity and exposure

As a consequence of the ubiquitous presence of PCDD/Fs and PCBs in the environment, these substances can also be found in food and animal feed at elevated levels. The main source for exposure for humans are food of animal origin, in particular products with a high lipid content. Several acute and in particular chronic toxic effects of PCDD/Fs and PCBs are described along with body half-lives proportional to age and body fat [3,4]. This includes adverse effects on the immune and reproductive system. PCDD/Fs are considered as human carcinogens. EFSA updated 2018 their risk assessment of PCDD/Fs and dioxin-like PCBs and concluded that the dietary intake in all age groups exceeds the new TWI of 2 pg TEQ/kg bw/week [5].

Analysis at EURL POPs

PCDD/Fs and PCBs are analysed according to Regulation (EU) 2017/644 for food and Regulation (EC) No 152/2009 for feed. Confirmatory methods allowing the unequivocal identification and quantification of PCDD/Fs and PCBs providing full information on congener basis and screening methods identifying samples with levels of PCDD/Fs and dioxin-like PCBs exceeding legal limits are described in these regulations.

The EURL applies different automated, semi-automated and manual clean-up methods for the analysis of PCDD/Fs and PCBs. For detection sector magnetic field mass spectrometry and tandem mass spectrometry are used.

For the analysis of PCDD/Fs in mineral feed, trace elements, pre-mixtures and compound feed a recommendation for extraction procedures was developed within the EURL/NRL network and published.

Legal requirements

Maximum levels for various food matrices are laid down in Regulation (EC) No 1881/2006. Additional action levels are defined (Recommendation 2013/711/EU) to serve as early warning tool in order to identify possible contamination sources.

References

  • [1] Stockholm Convention, The 12 initial POPs under the Stockholm Convention, last update 2008.

  • [2] Breivik, K.; Sweetman, A. et al., 2007. Sci. Total Environ. 377 (2-3):296-307.

  • [3] Kuratsune, M.; Yoshimura, T et al., 1972. Environ. Health Persp. 1: 119-128.

  • [4] O'Grady Milbrath, M.; Wenger, Y. et al., 2009. Environ. Health Persp. 117 (3): 417-425.

  • [5] EFSA CONTAM Panel et al, 2018. EFSA Journal 16(11):5333.

CPs What are CPs and where do they come from?

Chlorinated paraffins (CPs) are complex mixtures of certain organic compounds containing chlorine: polychlorinated n-alkanes. The chlorination degree of CPs can vary between 30 and 70%. Typically, CPs are further divided by carbon chain length into the groups short-chain CPs (SCCPs, C10-C13), medium-chain CPs (MCCPs, C14-C17) and long-chain CPs (LCCPs, C>17). They are commonly being uses as flame retardants and plasticizers in rubber, paints, adhesives and plastics where they migrate into the environment through evaporation or abrasion [1,2].

CP structure

Toxicity and exposure

Due to the very complex nature of chlorinated paraffins, not much is known about their toxicity. However, the persistent, bioaccumulative and partly toxic properties observed have led to SCCPs (C10-C13 CPs) being included in Annex A of the Stockholm Convention [3]. MCCPs and LCCPs are still under evaluation in several countries for similar properties [4]. EFSA concluded in its Scientific Opinion on CPs 2020 that based on the little data currently available in Europe, no immediate cause for health concern due to dietary exposure is indicated. Benchmark dose levels were established as 3.2 mg/kg body weight/day for SCCPs and 36 mg/kg body weight/day for MCCPs [5].

Analysis at EURL POPs

CPs are analysed at the EURL POPs using GC-ECNI-HRMS with Orbitrap technology and custom-made chain length specific quantification standards. The method is available as part of the Guidance Document on CP analysis.
Based on PT results [6] and discussions within the CWG CP, further investigations into optimization of the analytical workflow (quicker, easier sample preparation) are planned. Additionally, investigations into different methods of LOQ determination and the production/application of new quantification standards (in cooperation with the CHLOFFIN/REVAMP projects) will be continued. The method development is done in accordance with requirements by ISO 17025 accreditation.

Legal requirements

There are no legal requirements for CPs in food and feed at this time.

References

  • [1] D.C.G. Muir, 2010. Chlorinated paraffins: Handb. Environ. Chem. 10: 107–133.

  • [2] J.N. Hahladakis, C.A. Veliset al., Journal of hazardous materials 344 (2018) 179–199.

  • [3] Stockholm Convention, 2017. Decision SC-8/11.

  • [4] J. Glüge, L. Schinkel et al., Environ. Sci. Technol. 52 (2018) 6743–6760.

  • [5] EFSA CONTAM Panel et al., EFSA Journal 18 (2020) 225.

  • [6] K. Krätschmer, A. Schächtele, Chemosphere 234 (2019) 252–259.

PCNs What are PCNs and where do they come from?

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are a group of 210 different congeners (135 dibenzofurans and 75 dibenzo-p-dioxins) and polychlorinated biphenyls (PCBs) consist of 209 different congeners with different chlorination degrees and distribution patterns of the Cl-substituents on the phenyl rings [1]. PCDD/Fs are produced unintentionally in industrial and thermal processes. In contrast, technical mixtures of PCBs were used for several decades since the late 1980s in a wide range of different applications. Due to their persistence, PCDD/Fs and PCBs are found ubiquitous in various biotic and abiotic compartments and are bioaccumulated along the food chain [2].

PCN structure

Toxicity and exposure

Studies show an AhR-mediated mechanism of toxicity by PCNs because of the planar structure and similarity to 2,3,7,8-TCDD. Thereby high chlorinated PCNs show higher 2,3,7,8-TCDD relative potencies (REPs) than low chlorinated PCNs. In total the REPs of PCNs are comparable with those of the mono-ortho-PCBs thus a small contribution of PCNs to the total TEQ was reported [3]. The main route of exposure by PCNs for humans is dietary intake. Frequently detected PCN congeners in food are PCN-52, PCN-66/67 and PCN-73 [1].

Analysis at EURL POPs

EURL POPs is developing and optimizing multi-methods in order to monitor 26 CN-congeners in parallel with other POPs like Dioxins, PCBs or PBDEs. Congeners were selected based on toxicological significance and availability of reference standards. Frequently used extraction methods are hot pressurized liquid extraction, hot liquid extraction and cold liquid extraction. Sample clean-up is done with silica sulphuric acid column, alumina column and carbon column in routine. Used measurement techniques are APGC-MS/MS and GC-HRMS (sectorfield/ orbitrap).

Legal requirements

There are no legal maximum levels set so far.

References

  • [1] Fernandes A., Rose M., Falandysz J., 2017. Environ. Int. 104:1-13.

  • [2] Jakobsson E., Asplund L., 2000. Handb. Environ. Chem. 3 (K), chapter 5.

  • [3] Falandysz J., Fernandes A., et al., 2014. J. Environ. Sci. Health, C 32 (3), 239-272.

PBDEs What are PBDEs and where do they come from?

Polybrominated diphenyl ethers (PBDEs) are a class of organobromine compounds that are used as additive brominated flame retardant (BFR) chemicals. PBDEs have been used in a variety of industrial and domestic applications such as transport (vehicles, trains, aircraft, etc.), plastics, furnishings, insulation, paints, electronic goods, etc. Consumption peaked in the early 2000's, but some PBDEs are still extensively used worldwide. Their chemical and physical properties are similar to those of PCDD/Fs and PCBs. PBDEs constitute a group consisting of 209 possible congeners whose degree of bromination range from mono- to deca-brominated with the sum formula C12H(10−x)BrxO (x = 1, 2, ..., 10), although a considerably smaller number are actually formed during commercial production. Congeners are classified according to the number of bromine atoms in the molecule.

PBDE

Toxicity and exposure

Like other POPs, PBDEs are highly hydrophobic and highly resistant to degradation processes, particularly biodegradation, although photo degradation is known to occur. Accordingly, PBDEs have been detected in humans in all regions [1]. Adverse health effects have been reported for humans, animals and soil organisms. Due to their toxicity and persistence, the industrial production of technical PBDE mixtures such as “Penta-“, “Octa-“, and “Deca-BDE“ is restricted under the Stockholm Convention. EFSA derived 2011 benchmark dose lower limits (BMDL10) for eight PBDEs ranging 12-1700 µg/ kg bw based on available data. Only the dietary intake of BDE-99 is currently considered of health concern [2].

Analysis at EURL POPs

As a basis for official food control, COMMISSION RECOMMENDATION of 3 March 2014, on the monitoring of trace levels of brominated flame retardants in food (2014/118/EU) applies to the congener specific determination of PBDEs in food and animal feed matrices.

The establishment, optimization and validation of methods using different MS techniques for PBDE analysis (high resolution mass spectrometry versus GC-MS/MS techniques) with regard to selectivity and limits of quantification and for HBCDD analysis (HPLC-MS/MS for differentiation between α-, β- γ-HBCDD) will be continued. Other brominated contaminants regarded as relevant by the CWG Brominated contaminants and PCNs (e.g. tetrabromobisphenyl A, hexabromobenzene, 2,2',4,4',5,5'-Hexabromobiphenyl (PBB 153) and bromophenols (4-BP, 2,4-BP, 2,4,6-TBP)) are intended to be included in multi-methods or single methods will be established. The method development is done in accordance with requirements by ISO 17025 accreditation.

Legal requirements

There are no legal requirements for PBDEs in food and feed at this time.

More about PBDEs

References

  • [1] Antignac, J. P.; Main, K. M. et al., 2016. Environ. Pollut. 218: 728-738.

  • [2] EFSA CONTAM Panel et al., 2011. EFSA Journal 9(5):2156.

HBCDD What are HBCDDs and where do they come from?

Hexabromocyclododecane (HBCDD) is a manufactured organobrominated compound used as a flame retardant. The application and distribution is often simultaneous to PBDEs, commonly in expanded and extruded polystyrene for use in construction, as well as in furniture upholstery, vehicle interiors and packaging material, and in other applications such as insulation, paints, electronic goods, etc.
The commercial production of HBCDD generally results in the bromination pattern of 1,2,5,6,9,10-hexabromocyclododecane which comprises 16 possible stereoisomers. Of these, the α-, β- and γ-stereoisomers predominate in the technical product and are therefore most commonly present in food and feed.

HBCDD structure

Toxicity and exposure

Due to its persistence, toxicity, and eco-toxicity, the Stockholm Convention on Persistent Organic Pollutants decided in May 2013 to list HBCDD in Annex A to the Convention, which requires elimination of production. EFSA concluded in its updated risk assessment 2021 [1] based on available data, that adverse effects on neurodevelopment in mice are critical effects, leading to a lowest observed adverse effect level (LOAEL) of 0.9 mg/kg bw. The current dietary exposure to α-, β- and γ-HBCDD however does not raise health concern. Only lactational exposure of infants with high milk consumption might be of concern.

Analysis at EURL POPs

As a basis for official food control, COMMISSION RECOMMENDATION of 3 March 2014, on the monitoring of trace levels of brominated flame retardants in food (2014/118/EU) applies only to the diastereoisomer (diastereomer) specific determination of α-, β- and γ-stereoisomers of 1,2,5,6,9,10-HBCDD in food and animal feed matrices.

Legal requirements

There are no legal requirements for HBCDDs in food and feed at this time.

More about HBCCDs

References

  • [1] EFSA CONTAM Panel et al., 2021. EFSA Journal 2021; 19(3):6421.

eBFRs What are emerging BFRs and where do they come from?

Brominated flame retardants (BFRs) are used commonly in plastics, textiles and electrical/electronic equipment. Emerging and novel brominated flame retardants (eBFRs) are groups of brominated compounds (BCons) that mostly resulted from the legal actions taken against PBDEs, HBCDD and PCBs. Instead of focussing on one few compounds to replace the banned ones, industry developed a wide variety of fit-for-purpose brominated compounds. This led to a steadily increasing number of potentially critical compounds needing to be included in official food controls. EURL POPs’ Core Working Group BCons and PCNs developed a priority list based on available data in the literature, currently including the following analytes or analyte groups:

Common name
Polybrominated dibenzo-p-dioxins/furans
Pentabromobenzene
Hexabromobenzene
Pentabromotoluene
Pentabromoethylbenzene
1,2-bis((2,4,6-tribromophenoxy)ethane
Decabromodiphenylethane
Tetrabromo-p-xylene
Bis(2-ethylhexyl)-tetrabromophthalate
2-Ethylhexyl-2,3,4,5-tetrabromobenzoate
1-(1,2-Dibromoethyl)-3,4-dibromocyclohexane
2,4,6-Tribromophenol
2,4-Dibromophenol
4-Bromophenol
2,6-Dibromophenol
Tetrabromobisphenol A
IUPAC name
-
1,2,3,4,5-Pentabromobenzene
1,2,3,4,5,6-Hexabromobenzene
1,2,3,4,5-Pentabromo-6-methylbenzene
1,2,3,4,5-Pentabromo-6-ethylbenzene
1,1'-[1,2-Ethanediyl-bis(oxy)] bis[2,4,6-tribromo]benzene
1,1'-(1,2-Ethanediyl)bis[2,3,4,5,6-pentabromo-benzene]
1,2,4,5-Tetrabromo-3,6-dimethylbenzene
3,4,5,6-Tetrabromo-1,2-benzenedicarboxylic acid 1,2-bis(2-ethylhexyl) ester
2,3,4,5-Tetrabromobenzoic acid 2-ethylhexyl ester
1,2-Dibromo-4-(1,2-dibromoethyl)-cyclohexane
2,4,6-Tribromophenol
2,4-Dibromophenol
4-Bromophenol
2,6-Dibromophenol
2,6-dibromo-4-[2-(3,5-dibromo-4-hydroxyphenyl)propan-2-yl]phenol
Abbreviation
PBDD/Fs
PBBz
HBB
PBT
PBEB
BTBPE
DBDPE
TBX
BEH-TEBP
EH-TBB
DBE-DBCH
2,4,6-TBP
2,4-DBP
4-BP
2,6-DBP
TBBPA
CAS No.
-
608-90-2
87-82-1
87-83-2
85-22-3
37853-59-1
84852-53-9
23488-38-2
26040-51-7
183658-27-7
3322-93-8
118-79-6
615-58-7
106-41-2
608-33-3
79-94-7

Toxicity and exposure

Not much is known about the toxicity of most eBFRs, but EFSA identified in their 2012 Scientific Opinion BTBPE and HBB as compounds that could raise a concern for bioaccumulation. Predicted Overall persistence and potential for bioaccumulation, the most relevant factors to provide insight into the possibility that emerging or novel BFRs might accumulate in the food chain, were also high for PBT, PBEB and TBX [1].

TBBPA and other brominated phenols were assessed in separate Scientific Opinions [2,3]. They are mainly used in printed circuit boards and thermoplastics (e.g. in TVs). Dietary exposure to TBBPA in the European Union was classified as not raising a health concern [2], but data was insufficient to establish a health-based guidance value. Only one brominated phenol could be evaluated (2,4,6-TBP); EFSA established a NOAEL of 100 mg/ kg bw/day. However, available occurrence data did suggest it was unlikely to raise a health concern for EU consumers [3]. All EFSA Scientific Opinions on brominated compounds are currently under review to incorporate the new data available.

Analysis at EURL POPs

The EURL applies different automated, semi-automated and manual clean-up methods for the analysis of novel and emerging BFRs. For detection, GC- and LC methods combined with high resolution mass spectrometry and tandem mass spectrometry are used. Sample preparation methods combining eBFRs with other brominated (and potentially chlorinated) compounds are currently in development.

Legal requirements

There are currently no legal requirements for eBFRs available. The European Commission published a monitoring recommendation for several brominated contaminants in food including TBBPA, other brominated phenols, BEH-TEBP and EH-TBB based on the 2011/2012 EFSA opinions [4].

References

  • [1] EFSA CONTAM Panel et al, 2012. EFSA Journal 10(10):2908.

  • [2] EFSA CONTAM Panel et al, 2011. EFSA Journal 9(12):2477.

  • [3] EFSA CONTAM Panel et al, 2012. EFSA Journal 10(4):2634.

  • [4] Commission Recommendation 2014/118/EU of 3 March 2014 on the monitoring of traces of brominated flame retardants in food.